Field of the Invention
The present invention relates to a technical field of display, and more particularly, to polarity inversion driving method and apparatus for a liquid crystal display panel, and a liquid crystal display (LCD).
Description of the Related Art
In an existing thin-film-transistor liquid crystal display (abbreviated as TFT-LCD), the manner for performing polarity inversion (changing from a positive polarity into a negative polarity or changing from a negative polarity into a positive polarity) is shown in FIG. 1. As shown in FIG. 1, the solution in the prior art includes a polarity control signal POL, a cache module B, a first channel selection module C1, a voltage selection channel L and a second channel section module C2, wherein the voltage selection channel L includes a positive-polarity-voltage selection channel L1 and a negative-polarity-voltage selection channel L2, and a signal, which is output from the positive-polarity-voltage selection channel, provides a corresponding positive polarity voltage, and a signal, which is output from the negative-polarity-voltage selection channel, provides a corresponding negative polarity voltage.
The cache module B receives from outside a first grayscale signal D1 and a second grayscale signal D2, and outputs them respectively to the first channel selection module C1 where the driving capacity of the first and second grayscale signals is enhanced. A first input port 3 and a second input port 4 of the first channel selection module C1 respectively receive the first grayscale signal and the second grayscale signal from a first output port 1 and a second output port 2 of the cache module B. Corresponding voltage selection channels are selected by the first channel selection module C1 for the first and second grayscale signals according to the polarity control signal, and the selection manner is shown in FIGS. 2A and 2B.
Referring to FIG. 2A, when the polarity control signal is at a high level, the first grayscale signal is input into the positive-polarity-voltage selection channel L1 via the first channel section module C1 and then provides a positive polarity voltage corresponding to the first grayscale signal to a first output port OUT1 via the second channel selection module C2; and the second grayscale signal is input into the negative polarity voltage section channel L2 via the first channel section module C1 and then provides a negative polarity voltage corresponding to the second grayscale signal to a second output port OUT2 via the second channel selection module C2.
Referring to FIG. 2B, when the polarity control signal is at a low level, the first grayscale signal is input into the negative-polarity-voltage selection channel L2 via the first channel section module C1 and then provides a negative polarity voltage corresponding to the first grayscale signal to the first output port OUT1 via the second channel selection module C2; and the second grayscale signal is input into the positive polarity voltage section channel L1 and then provides a positive polarity voltage corresponding to the second grayscale signal to the second output port OUT2 via the second channel selection module C2.
The first output port OUT1 is connected with pixel electrodes of sub-pixels in an odd-number column, and the polarity voltage corresponding to the first grayscale signal and output by the first output port is the voltage of the pixel electrode of the sub-pixels in the odd-number column, and the second output port OUT2 is connected with pixel electrodes of sub-pixels in an even-number column, and the polarity voltage corresponding to the second grayscale signal and output by the second output port is the voltage of the pixel electrode of the sub-pixels in the even-number column.
In existing solutions, based on different polarity control signals, a 1-dot polarity inversion mode, a 2-dot polarity inversion mode, a 1-dot+2-dot polarity inversion mode, and a 4-dot polarity inversion mode and the like may be achieved.
In the above modes, the 1-dot polarity inversion mode has the best display effect, and its polarity inversion manner is shown in FIG. 3. As shown in FIG. 3, an interference strip (noise) is invisible in the 1-dot polarity inversion mode, and the invisibility is resulted from close spacing between polarity inversion positions, specifically, since the polarity inversion in each line will affect data signals, the comprehensive effect is not obvious or there is cancelling out of one another. However, the power consumption of the display in the 1-dot polarity inversion mode is relatively high, thus the 1-dot+2-dot polarity inversion mode or the 2-dot polarity inversion mode is applied in most of the products, which may reduce power consumption while having little effect on the display effect.
In the TFT-LCD panel, it is very difficult to ensure complete uniformity of TFT characteristics. When the 1-dot+2-dot polarity inversion mode or the 2-dot polarity inversion mode is applied, there is some difference in charging rate between the TFTs in the polarity inversion line and the TFT in the subsequent line of the same polarity. If the difference reaches a certain level, a grayscale difference occurs, thus equally spaced strips (interference strips) will be observed, and the interference strips are concentrated in one certain line.
Further, in a data-line driving polarity inversion mode in a low frequency, if there is relative movement (in the upper and lower viewing angle range) between the observer and the display panel, the interference strips are easier to be observed, and a strip interval is the same as a polarity inversion interval. For example, in the 2-dot polarity inversion mode shown in FIG. 4, the next line below the black line is the location where the interference strip appears. It can be seen from FIG. 4 that if a 2-dot polarity inversion mode is used, the strip interval is of a two-dot width. FIG. 5 is a schematic view showing a 1-dot+2-dot polarity inversion mode, and it can be seen therefrom that the strip interval is of a two-dot width. FIG. 6 is a schematic view showing a 4-dot polarity inversion mode, and it can be seen from FIG. 6 that the strip interval is of a four-dot width.